1. Field of the Invention
The present invention relates to a driving method for driving an electro-optical device that performs gray scale display control through pulse-width modulation, a driving circuit for the electro-optical device, and electronic equipment.
2. Description of Related Art
Electro-optical devices, such as a liquid-crystal display device employing a liquid crystal as an electro-optical material, are now replacing cathode ray tubes (CRTs), and are widely used as a display of a variety of information processing apparatuses or of wall-mounted television sets.
A conventional electro-optical device typically includes an element substrate on which a matrix of pixel electrodes and switching elements, such as TFTs (Thin-Film Transistors), respectively connected to the pixel electrodes, are formed, an opposite substrate on which an opposite electrode, opposed to the pixel electrodes, is formed, and a liquid crystal, as an electro-optical material, encapsulated between the two substrates. With this arrangement, when a scanning signal is applied to the switching element through a scanning line, the switching element becomes conductive. When the pixel electrode is applied with an image signal having a voltage responsive to the gray scale thereof through a data line during the conductive state of the switching element, a charge responsive to the voltage of the image signal is stored in a liquid crystal layer between the pixel electrode and the counter electrode. Even if the switching element is turned off subsequent to the storage of the charge, the storage of the charge is maintained in the liquid crystal layer by capacitance of the liquid crystal itself and a storage capacitor formed between the two substrates. When each switching element is driven and the stored charge is controlled in accordance with the gray scale, the alignment of the liquid crystal in each pixel changes, and brightness can be controlled from pixel to pixel. A gray scale display thus results.
Since a period of time during which the charge is stored in the liquid crystal layer in each pixel is part of a scanning period, a time-division multiplex driving method becomes possible in which a plurality of pixels share the same scanning line or the same data line. In this driving method, first, a scanning line driving circuit sequentially selects the scanning lines, second, a data line driving circuit sequentially selects the data lines during a selection period of the scanning line, and third, the selected data line thus samples the image signal having a voltage responsive to the gray scale thereof.